The 204Y is a heteroplasmy, which means the person has some mtDNA with the CRS's T variant and some the the normal mutation's C variant. I think of heteroplasmies as "mutations-in-progress." It is rare to "capture" one in progress between generations.

FTDNA's matching system is supposed to disregard heteroplasmies. But as you have noticed it only works one way. The person with the heteroplasmy sees those without as matches, but the one without the heteroplasmy does not see the one with the heteroplasmy as a match. FTDNA has known about the problem for quite a while, but either can't fix it or doesn't have it on its priority list.

FTDNA's reasoning for not showing one-off mtDNA matches is that they normally would not be connected within a few thousand years. But that doesn't apply with heteroplasmies. They also disregard the 309.1C insertion. I have two K Project members who have a perfect FGS match, including one or more rare coding-region mutations, except that one has 16093C and the other doesn't. In my opinion, 16093C is not much better than 309.1C. In our case, I put the two people in contact.

So, the immediate solution is to join an mtDNA haplogroup project where the administrator is alert to such issues and takes an active approach to solving the problems. Good luck.

Bill Hurst

> All,
>
> I manage the Fernandes DNA Surname Project, where I also allow the display of mtDNA results - as this is an Iberian surname, and in Iberia last names are often inherited matrilineally.
>
> If you take a look at our results section ( http://www.familytreedna.com/public/Fernandes/default.aspx?section=mtresults ), you will notice two individuals in the C1 haplogroup, 186136 and 190662. 186136 is 190662's son and they both have ordered the FGS test (not displayed due to privacy reasons). In any case, you will notice that the son has a mutation in the HVR2 panel (204Y) not presented by the mother. This is interesting in itself, because if we did not know they were related, we would assume there was just "50% chance the MRCA lived 1300 years ago."
>
> This is because - and here is what is more interesting to me - the mother does not see the son as a match on the HVR2 panel, nor under the FGS results. The son, however, does see the mother as a match under both HVR2 and FGS. The implication is that if your mtDNA line has remained unchanged while a close relative has had a mutation, you will not be aware that the individual is so close to you - you will not see them as a match under HVR2 or beyond.
>
> How often does this happen (a close relative having an "unexpected" mtDNA mutation like this) and how many matches are we missing in our genealogical explorations due to the way FT DNA displays these results?
>
> Best regards,
> Aaron Torres